This invention relates generally to cleaning methods, and more particularly to a novel cleaning method for sterilizing an artificial kidney (i.e., a kidney dialyzer) with ozonated water. This invention also relates to an apparatus for producing ozonated water used during the performance of the cleaning method.
Disposable artificial kidneys have been reprocessed and reused in chronic hemodialysis for more than twenty years. Reuse of artificial kidneys has clearly become a standard medical practice in the United States, wherein over seventy percent of dialysis facilities are reusing artificial kidneys. These facilities treat over seventy percent of the dialysis patients in the United States.
Other than by hand washing the artificial kidney or dialyzer, there are two well-known methods for sterilizing the dialyzer. One such method, as shown in FIG. 1, is a method utilizing heat to clean the dialyzer. More specifically, the dialyzer is subjected to manual rinsing using purified water. The dialyzer then is rinsed with purified water, reverse filtered (also with purified water) and tested in an automated reuse apparatus which is well-known in the art. The dialyzer is then subjected to 105 degrees Celsius for a period of twenty-four hours for sterilization purposes. A disadvantage of this method is that it takes too long to complete, especially for hospitals, and other medical facilities, having many patients requiring dialysis. Another disadvantage is that the dialyzer does not tolerate being subjected to high temperatures very well (e.g., the dialyzer becomes cracked, or it may melt) which results in fewer reuses thereof The other known method follows the same prescribed method as heat treating, except instead of subjecting the dialyzer to heat over a period of time, suitable chemicals are used to sterilize it. This method is disclosed in FIG. 2. Various chemicals or sterilizing agents which are presently used are: CIDEX.RTM.; DIACIDE.RTM.; SPORICIDIN.RTM.-hd; formaldehyde; RENALIN.RTM.; and peracetic acid. While taking less time than heat treating (approximately two and one half hours), one problem associated with using chemicals is that there is a risk that the chemicals may remain inside the dialyzer and pose a threat to the patient during subsequent use of the dialyzer. Another drawback is that the chemicals are difficult to dispose of after they have been used. Moreover, many of the aforementioned chemicals are very expensive.
Ozone has been used as a sterilizing agent in the past. For example, in U.S. Pat. No. 5,266,275 to Faddis, there is disclosed a method and apparatus for sterilizing medical instruments using ozone. However, ozone has never heretofore been used to sterilize a used dialyzer.
Thus, there is presently a need for a method of sterilizing a used dialyzer which is not time-consuming and which leaves the dialyzer free of chemicals and other contaminants.
The present invention is directed to a method for cleaning an article, such as a used kidney dialyzer, requiring sterilization comprising the steps of: (a) manually rinsing the article with purified water; (b) inserting the article into an automated reuse apparatus which utilizes ozonated water; and (c) sterilizing the article for a predetermined period of time with ozonated water, the ozonated water flowing through the article for sterilizing it. More specifically, the step of inserting the article into the automated reuse apparatus comprises the steps of: rinsing the article with ozonated water; reversing the flow of ozonated water through the article for backwashing the article; and conducting testing cycles wherein the article is tested for leaks therein and for ensuring it can contain a predetermined quantity of fluid. Preferably, the predetermined period of time of the sterilizing step is approximately thirty minutes.
An apparatus for producing ozonated water of the present invention comprises a container defining a chamber. The container has a first inlet for introducing purified water into the chamber, a second inlet for introducing vaporized ozone into the chamber, and an outlet for venting ozonated water from the chamber. A pump siphons ozonated water from the chamber of the container via the outlet of the container. Suitable introducing means is provided for introducing vaporized ozone into the chamber of the container through the second inlet. A sensor measures oxygen reduction potential (ORP) of the ozonated water, and controls the amount of vaporized ozone introduced into the chamber of the container by the introducing means.
The introducing means of the apparatus specifically comprises a venturi injector in fluid communication with the second inlet of the container for injecting vaporized ozone therein. A device is provided for manufacturing oxygen, and an ozone generator, in fluid communication with the device and with the venturi injector, creates ozone which is then delivered to the venturi injector. A level control regulates the level of ozonated water contained within the chamber by introducing purified water therein when the level of ozonated water is below a predetermined quantity. Moreover, a filter is in fluid communication with the chamber of the container for further filtering and purifying the ozonated water contained within the chamber of the container.
Accordingly, among the several objects of the present invention are the provision of an improved method for cleaning a used dialyzer requiring sterilization which requires less time than other known methods; the provision of such an improved method which leaves the dialyzer completely clean without substantially any residue from chemicals or other contaminants being left thereon which present a potential risk to the patient and to employees handling the dialyzer; the provision of such a method which is a cost-effective alternative to known prior methods of sterilization; the provision of such a method which is capable of utilizing existing cleaning equipment; the provision of such a method which enables the dialyzer to be used immediately after completion of the cleaning method; and the provision of such a method which is easy to perform, simple to implement, and which little or no specialized training is required for persons conducting the method.
Also among the several objects of the present invention are the provision of an apparatus for producing ozonated water which is compact in construction and can deliver ozonated water to a device requiring the same on site; the provision of such an apparatus which produces sterilized ozonated water suitable for medical use; and the provision of such an apparatus which is easy to operate, simple in construction, and cost-efficient to manufacture and operate.